To solve the Laplace equation on a rectangular domain with given nonho
mogeneous Dirichlet boundary conditions, separation of variables is fr
equently used. However the convergence of the resulting series solutio
n will often be slow, due to the presence of Gibb's effects. A simple
trick can avoid this and greatly increase the speed of convergence. Th
is can illustrate to students how use of mathematical insight can give
a practical benefit.